A sociologist says the death of two-year old Shelby Duis in Spirit Lake has focused attention on abuse cases, but it’s also part of a growing trend in Iowa. Duis’ mother and her boyfriend are accused of killing the girl. Drake University sociologist Dean Wright says today’s relationships have led to more cases where a man is involved abusing his girlfriend’s children.Wright says more and more people are living in partnerships without a traditional family bond. He says the male is often frustrated with young children in such a relationship. Wright says older kids aren’t immune from the problem, and they’re often asked to leave when a new boyfriend enters a relationship.The death of Duis has created a controversy over how reports of possible abuse were handled by the state. Wright says these cases in general are getting more attention through efforts to stop child abuse.Wright says the abusers in these cases are often part of another societal trend — an increase in the agression among people. Wright says the one positive from the Duis case may be an increased awareness of the problem and more aggressive reporting of suspected child abuse.